The radiologist and the cytologist in diagnosing thyroid nodules: results of cooperation

Diagnostic Significance of Ultrasound-Guided Fine-Needle Aspiration Biopsy and on-Site Assessment by Pathologists for Thyroid Micronodules

Objective

Ultrasound-guided fine-needle aspiration biopsy (US-FNAB) is a safe and effective method for screening malignant thyroid nodules. The purpose of this study was to compare the diagnostic effectiveness of US-FNAB for nodules of different sizes.

Methods

A total of 1085 patients with thyroid nodules who underwent US-FNAB between January 2021 and July 2023 were included in the study. The patients were divided into three groups based on the maximum diameter of the nodules: there were 324 patients with thyroid nodules ≤5 mm in Group A, 537 patients with thyroid nodules between 6 mm and 10 mm in Group B, and 224 patients with thyroid nodules >10 mm in Group C. The US-FNAB satisfactory specimen rate, biopsy time and cytopathological results for the three groups were collected and compared with the postoperative pathological results.

Results

The US-FNAB satisfactory specimen rates for Groups A, B and C were 84.57% (274/324), 90.13% (484/537) and 94.64% (212/224), respectively. The average biopsy times for Groups A, B, and C were 100.84 ± 41.58 s, 91.20 ± 32.53 s, and 79.01 ± 29.62 s, respectively. In Groups A, B, and C, 103, 192 and 73 patients, respectively, underwent surgery, and the malignancy rates were 88.35%, 85.42% and 72.6%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of US-FNAB in Group A were 78.26%, 81.82%, 97.30%, 31.03%; respectively; those in Group B were 73.78%,85.71%,96.80%, and 35.82%, respectively; and those in Group C were 75.47%, 85.00%, 93.02% and 56.67%, respectively.

Conclusion

The US-FNAB satisfactory specimen rate for thyroid nodules ≤5 mm was relatively low, but the size of nodules had no effect on the diagnostic sensitivity of US-FNAB; additionally, nodules ≤5 mm had a higher probability of malignancy. Therefore, it is necessary to perform US-FNAB for thyroid nodules with a diameter ≤5 mm with malignant signs.

Increased diagnostic sensitivity of palpation-guided thyroid nodule fine-needle aspiration cytology by BRAF V600E-mutation analysis

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer and its incidence is increasing. Preoperative diagnosis is warranted in order to avoid 'two-stage' procedures that are associated with additional costs and higher radioactive iodine remnant uptake. In the setting of thyroid cancer, somatic BRAF V600E-mutations are highly specific for PTC and can be analyzed in aspirates from fine-needle aspiration cytology (FNAC). The 'gold standard' to perform FNAC is ultrasound guidance. Here, we analyze whether adding BRAF V600E-mutation analysis could be of value in palpation-guided FNACs. A total of 430 consecutive patients were included. Ultrasound-guided FNACs were performed in 251 patients and 179 patients underwent palpation-guided FNACs. BRAF V600E-mutation analysis was performed using two methods, an allele-specific polymerase chain reaction (PCR) analyzed by capillary gel electrophoresis (PCR/Qiaxcel), and a droplet digital PCR (ddPCR) assay. A total of 80 patients underwent surgery, and histology revealed 25 patients to have PTC. Of the 25 PTCs, 23 (92%) showed a BRAF V600E-mutation. Both mutation analysis methods (PCR/Qiaxcel and ddPCR) produced concordant results. In the ultrasound-guided group, the preoperative diagnostic sensitivity of FNAC using the Bethesda classification alone was very high and additional BRAF V600E-mutation analysis added little to the preoperative diagnostic sensitivity. By contrast, in the palpation-guided group, by adding BRAF V600E-mutation analysis, eight instead of four patients were diagnosed of having PTC. This increase in the diagnostic sensitivity was statistically significant (p < 0.05). The costs per sample were as low as 62 USD (PCR/Qiaxcel and ddPCR) and 35 USD (PCR/Qiaxcel only). Ultrasound-guided FNAC should be aimed for when dealing with thyroid nodules. However, if palpation-guided FNAC cannot be avoided or may be required due to resource utilization, adding BRAF V600E-mutation analysis using the methods described in this study might significantly increase the proportion of preoperatively diagnosed PTCs. The additional costs can be considered very reasonable.

Ultrasonic elastography and conventional ultrasound in the diagnosis of thyroid micro-nodules

Objective:

To investigate the clinical value of conventional ultrasound, ultrasound elastography and conventional ultrasound combined with ultrasound elastography in differential diagnosis of benign and malignant thyroid micro-nodules.

Methods:

Eighty-six patients who were found with thyroid micro-nodules with the maximum diameter no more than 10 mm in the physical examination in our hospital from June 2015 to December 2017 were selected, and 102 nodules were included. All patients were confirmed with thyroid micro-nodules by puncture or surgical pathology and underwent conventional ultrasound and ultrasound elastography. Taking the surgical pathological results as a control, the value of conventional ultrasound, ultrasound elastography and conventional ultrasound combined with ultrasound elastography in differential diagnosis of benign and malignant thyroid micro-nodules were compared. A receiver operating characteristic (ROC) curve was drawn, and the area under the ROC curve was calculated.

Results:

One hundred and two thyroid nodules were detected by surgical pathology, including 75 benign nodules (73.53%) and 27 malignant nodules (26.47%). The sensitivity and diagnostic accordance rate of ultrasound elastography were significantly higher than those of conventional ultrasound in the diagnosis of thyroid microcarcinoma, and the missed diagnosis rate of ultrasound elastography was significantly lower than that of conventional ultrasound; the difference was statistically significant (P<0.05). However, the difference between the two methods was not statistically significant in terms of diagnostic specificity and misdiagnosis rate (P>0.05). The areas under the ROC curve in the diagnosis of benign and malignant thyroid nodules by conventional ultrasound and ultrasound elastography were 0.735 and 0.743 respectively.

Conclusion:

Conventional ultrasound can be used as a routine examination technique in differential diagnosis of benign and malignant thyroid nodules, while ultrasound elastography can improve the sensitivity and diagnostic rate in the diagnosis of thyroid micro carcinoma. It can help to reduce the clinical missed diagnosis, which also can be be used as an effective supplement for conventional ultrasound.

Role of operator experience in ultrasound-guided fine-needle aspiration biopsy of the thyroid

PURPOSE

Thyroid nodules are commonly encountered in clinical practice, and ultrasound (US)-guided fine-needle aspiration biopsy (FNAB) is the gold standard in diagnosing the pathological nature of undetermined thyroid nodules. The aim of this study was to evaluate whether operator experience influences the diagnostic accuracy of US-guided FNAB.

MATERIALS AND METHODS

A total of 700 consecutive US-guided FNAB done by a single radiologist between 2000 and 2007 were retrospectively analysed. The same freehand technique and capillary-action technique with 22- or 25-gauge needles was used for all nodules, All specimens were prepared and fixed without the cytologist on site and were subsequently analysed by two expert cytologists. The procedures were chronologically divided into seven groups and classified as diagnostic or nondiagnostic.

RESULTS

The rate of nondiagnostic procedures for each group was 32% in group 1, 13% in group 2, 17% in group 3, 11% in group 4, 10% in group 5, 5% in group 6 and 8% in group 7. No major complications were recorded.

CONCLUSIONS

The rate of nondiagnostic US-guided FNAB is heavily dependent on the operator's experience. We estimated that at least 200 procedures need to be performed in order to achieve the levels of diagnostic accuracy reported in the literature. We therefore suggest specific training before operators routinely perform this procedure in clinical practice.